My Kepler Bb humanoids have a digestive system that is similar to ours but also in 2 anatomical ways, different. The 1 anatomical difference that gives these humanoids more energy is, wait for it, their appendix. Please Register or Log in to view the hidden image! Now this is a normal human appendix, only a few inches long. But a Kepler Bb humanoid's appendix is at least 3 times as long. With this added length, more good bacteria can be safely tucked away when the humanoid is ill and cellulose can be digested into simple sugars and absorbed into the bloodstream. This coupled with an overall higher BMR(basal metabolic rate) means that they get more energy from the same kinds of food than we do, particularly from plants. Now their other anatomical difference related to digestion is that they have 2 stomachs, 1 of which is just like ours and the other being inverted along the L->R axis. Please Register or Log in to view the hidden image! As you can see here, the gastric sphincter between the 2 stomachs is right in the middle of the first stomach. Now most of the time, food just gets digested in the first stomach both mechanically and chemically. But there are 3 cases in which the gastric sphincter will open and food will go into the second stomach. 1 of those is gluttony in which the gastric sphincter will stay open until there is a more comfortable amount in the first stomach. The other is illness during which any food that is eaten will go into the second stomach with as little time in the first stomach as possible to avoid vomiting up food. In fact both of these cases are to avoid vomiting up food. But there is 1 other case that is more interesting. Digestion of bone. You see, these humanoids eat a lot of bone, especially when they are either children going through growth spurts or pregnant women. Now the lower age limit for eating bone is 5 years and it is that way for a good reason. Any younger than 5 years and the esophagus will literally be scraped to the point of bleeding by eating bone. If this happens, a lot of blood can get into the first stomach and the child will vomit the blood back up. This can aggravate the esophageal scrape and thus worsen the bleeding which leads to more vomiting. While yes, with rehydration therapy the bone will get digested and the esophagus will heal, the child can easily become anemic this way. And yes bone marrow has a high iron content so the anemia would easily be corrected. But it is just not worth it to eat bone when the humanoid is below 5 years old. An anemic humanoid below 5 would be better off eating liver than bone to correct their low iron because then at least there won't be bleeding and vomiting. Anyway, the digestion of bone in the second stomach is very slow. Even with the bone digesting enzymes it secretes, it can still take hours to digest the amount of bone in an average meal depending on how thick the bone is. The meat itself, the muscle is digested much faster than this. And even though a higher amount of stomach acid speeds up the process, it doesn't speed it up by all that much. Once the bone has been digested, the gastric sphincter opens to let the second stomach push the digested bone into the first stomach to let it out into the intestines via the pyloric sphincter. But I was wondering, is there a better way to digest bone without risking bleeding in the intestines and while still having the defense against vomiting food provided by the second stomach being in the position that it is? Could anything other than enzymes and amount of stomach acid speed up the process?